Large volume submersible pumps, commonly used in oil well production, have a submersible electrical motor that rotates a shaft. The shaft extends through a seal section into a centrifugal pump for rotating the pump. In the seal section, there are several partitions through which the shaft passes. At the entrance and exit of the seal section and in the partitions, mechanical face seals are mounted to seal the interior from exterior well fluid.
A typical mechanical face seal has an annular stationary member that is mounted to the wall structure. A rotating seal member is coupled to the shaft to rotate with the shaft. The rotating seal member has a face that is urged into contact with the stationary face by means of a coil spring. A pressure compensator in the motor section or seal section provides a low pressure differential between the interior lubricant and the exterior well fluid. The seal members reduce lubricant leakage to the exterior, and well fluid leakage into the pump from the exterior.
Normally, the faces of the rotating and stationary seal rings are planar, smooth surfaces. For differing reasons, proposals have been made in the prior art to apply various configurations of grooves to the faces of mechanical face seals in general.